osem-fcy/app/models/contact.rb

class Contact < ActiveRecord::Base
  belongs_to :conference

  validates :conference, presence: true
  # Conferences only have one contact
  validates :conference_id, uniqueness: {message: 'has already contact details'}

  validates :facebook, :twitter, :googleplus, :instagram,
            format: URI::regexp(%w(http https)), allow_blank: true

  def has_social_media?
    return true if !facebook.blank? || !twitter.blank? || !googleplus.blank? || !instagram.blank? || !email.blank?
    false
  end
end